Professor Yasamin Mostofi and her team were able to successfully measure the occupancy of a room (despite the fact that people didn't have WiFi carrying devices such as smartphones with them) using WiFi.

By placing two WiFi cards in a 70-square-meter space Mostofi was able to count the number of people in that area using the strength of the WiFi signal.

The entire experiment is based on multi-path fading -- a phenomenon that happens when a human body attenuates and scatters WiFi signals. By analysing the strength of the received WiFi signal, the researchers were able to gauge the number of people in a room.

Mostofi's experiment has only worked on a small scale within a room of nine people but she claims the results could be used for wider applications including estimating the 'level of occupancy' in shopping centres, offices and homes.

Since the process doesn't require the need for a smartphone, these findings could also be applied to emergency situations or as Mostofi's lab states, to potentially 'counting behind walls.'

What the team fail to mention is how big firms and governments could use WiFi to monitor the whereabouts of people without their knowledge.

Her results are scheduled to be published in the Institute of Electrical and Electronics Engineers Journal.